Under Attack: Fungal Landscape of Spring Barley From Seedling Emergence to Harvest During a Severe Puccinia Hordei Epidemic

All plant tissues from leaves, stems and roots are hosting a wide diversity of fungal species. Our understanding of the assembly of this diversity of fungi during the plant growth cycle is limited. Here, we characterized the mycobiome of three spring barley cultivars at weekly intervals from seedling emergence to senescence and seed maturity. A notable proportion of members of the fungal communities were shared among different plant organs, but community dynamics were tissue specific. A severe attack of Puccinia hordei occurring during the vegetative stage had profound effects on the mycobiome, and P. hordei biomass displaced that of other taxa. Plant tissue type was the most important factor determining the mycobiome, but also plant age was contributing significantly. Using a random forest model, we found that specific members of the mycobiome were responding differently to plant age. A co-occurrence network analysis revealed complex interactions among fungal OTUs, and network connectivity was changing as per plant growth stage and plant tissue type. This study contributes to the understanding of assembly of fungal communities in cereals by providing a detailed atlas of fungal communities associated with barley. This knowledge will be vital for microbiome assisted plant health management and our study will serve as an important baseline for future efforts to harness microbiota in cereal health.